# Did an extraterrestrial impact or airburst occur at the onset of the Younger Dryas, about 12,800 years ago? · Younger Dryas impact hypothesis > Four answers have been proposed. No impact or airburst occurred; the proposed markers are terrestrial or background cosmic material… leads, with evidence… Source: https://mysteriesdept.com/mysteries/younger-dryas-impact/questions/QST0D51X8AJ1304/did-an-extraterrestrial-impact-or-airburst-occur-at-the Publisher: Mysteries Department Licence: CC BY 4.0 (credit Mysteries Department and link the page) Updated: 2026-10-26T11:59:09+00:00 --- **0** # Did an extraterrestrial impact or airburst occur at the onset of the Younger Dryas, about 12,800 years ago? Asked 26 Oct 2026 by [**apollo** ](https://mysteriesdept.com/u/apollo)·4 answers·0·0 following **Most likely: no impact or airburst occurred; the proposed markers are terrestrial or background cosmic material…** Ahead on the evidence, not yet confirmed. It needs two reviews to be accepted. ## Where it stands Four answers have been proposed. No impact or airburst occurred; the proposed markers are terrestrial or background cosmic material… leads, with evidence 2 for, 1 against: supported by its tests. Three are still possible. Of the two narrower questions under it, none is answered yet. ## Why it matters Everything else in the hypothesis depends on this. The proposed effects on climate, fire, megafauna and people only follow if a cosmic event of continental scale happened at the onset⁠[[1]](https://mysteriesdept.com/sources/SRC0D51WPR222ST/evidence-for-an-extraterrestrial-impact-12-900-years-ago); the mainstream review holds that the evidence for one fails at every step⁠[[2]](https://mysteriesdept.com/sources/SRC0D51WTWW7YV8/comprehensive-refutation-of-the-younger-dryas-impact). ## Answers 4 [**No impact or airburst occurred; the proposed markers are terrestrial or background cosmic material…** ](https://mysteriesdept.com/mysteries/younger-dryas-impact/answers/ANS0D51XBQY621Q/no-impact-or-airburst-occurred-the-proposed-markers-are) Supported by its tests Evidence: 2 for, 1 against Most likely [**A small or differentiated extraterrestrial body (such as an iridium-poor iron meteorite) left the Greenland…** ](https://mysteriesdept.com/mysteries/younger-dryas-impact/answers/ANS0D51XCQ621B8/a-small-or-differentiated-extraterrestrial-body-such-as-an) Not tested enough to call either way Evidence: 1 for, 1 against Still possible [**Airbursts and impacts from a large fragmenting comet deposited a synchronous boundary layer with impact…** ](https://mysteriesdept.com/mysteries/younger-dryas-impact/answers/ANS0D51XA183EE5/airbursts-and-impacts-from-a-large-fragmenting-comet) Failed a test; not refuted outright Evidence: 2 for, 4 against Disputed [**None of these.** ](https://mysteriesdept.com/mysteries/younger-dryas-impact/answers/ANS0D51XDEM7P6T/none-of-these) Not tested enough to call either way Evidence: none yet Still possible ## History 1. 2007[Firestone et al. puts forward: airbursts and impacts from a large fragmenting comet deposited a synchronous boundary layer with impact…](https://mysteriesdept.com/sources/SRC0D51WPR222ST/evidence-for-an-extraterrestrial-impact-12-900-years-ago) 1. 2010[Daulton et al.: electron microscopy identified claimed nanodiamonds as graphene and graphene-oxide aggregates.](https://mysteriesdept.com/sources/SRC0D51WQ7P4MZC/no-evidence-of-nanodiamonds-in-youngerdryas-sediments-to)For: No impact or airburst occurred; the proposed markers are terrestrial or background cosmic material… 1. 2013[Petaev et al. puts forward: a small or differentiated extraterrestrial body (such as an iridium-poor iron meteorite) left the Greenland…](https://mysteriesdept.com/sources/SRC0D51WQZ44MRA/large-pt-anomaly-in-the-greenland-ice-core-points-to-a) 1. 2013[Wittke et al.: proponents report boundary-layer peaks at dozens of sites in North America, Europe, the Middle East and…](https://mysteriesdept.com/sources/SRC0D51WR6Y55NF/evidence-for-deposition-of-10-million-tonnes-of-impact)For: Airbursts and impacts from a large fragmenting comet deposited a synchronous boundary layer with impact… 1. 2013[Petaev et al.: the GISP2 spike has Pt/Ir ratios above all known terrestrial and chondritic materials and very high Pt/Al…](https://mysteriesdept.com/sources/SRC0D51WQZ44MRA/large-pt-anomaly-in-the-greenland-ice-core-points-to-a)For: A small or differentiated extraterrestrial body (such as an iridium-poor iron meteorite) left the Greenland… 1. 2014[Meltzer et al.: only 3 of the 29 claimed sites have age control placing the layer at the onset.](https://mysteriesdept.com/sources/SRC0D51WRER0TD5/chronological-evidence-fails-to-support-claim-of-an)Against: Airbursts and impacts from a large fragmenting comet deposited a synchronous boundary layer with impact… 1. 2016[Holliday et al.: the Lubbock Lake blind test found microspherules and nanodiamonds low or absent at the boundary and abundant…](https://mysteriesdept.com/sources/SRC0D51WS6643R2/a-blind-test-of-the-younger-dryas-impact-hypothesis)For: No impact or airburst occurred; the proposed markers are terrestrial or background cosmic material… 1. 2022[Kenny et al.: no crater dates to the onset; the Hiawatha structure is about 58 million years old.](https://mysteriesdept.com/sources/SRC0D51WTN231HN/a-late-paleocene-age-for-greenlands-hiawatha-impact)Against: Airbursts and impacts from a large fragmenting comet deposited a synchronous boundary layer with impact… 1. 2023[Holliday et al. puts forward: no impact or airburst occurred; the proposed markers are terrestrial or background cosmic material…](https://mysteriesdept.com/sources/SRC0D51WTWW7YV8/comprehensive-refutation-of-the-younger-dryas-impact) 1. 2025[Green et al.: the GISP2 platinum spike has no agreed terrestrial source.](https://mysteriesdept.com/sources/SRC0D51WX364VFQ/a-possible-volcanic-origin-for-the-greenland-ice-core-pt)Against: No impact or airburst occurred; the proposed markers are terrestrial or background cosmic material… 1. 2025[Green et al.: the spike lasts about 14 years, which fits a fissure eruption better than an instantaneous event.](https://mysteriesdept.com/sources/SRC0D51WX364VFQ/a-possible-volcanic-origin-for-the-greenland-ice-core-pt)Against: A small or differentiated extraterrestrial body (such as an iridium-poor iron meteorite) left the Greenland… 1. 2026[The PLOS One Editors: two 2025 papers adding Baffin Bay cores and shocked quartz were retracted for failures of age model and…](https://mysteriesdept.com/sources/SRC0D51WWKJ0X43/retraction-shocked-quartz-at-the-younger-dryas-onset-12-8-ka)Against: Airbursts and impacts from a large fragmenting comet deposited a synchronous boundary layer with impact… 1. 26 Oct 2026Asked on this site ## Discussion 0 [Add to the discussion](https://mysteriesdept.com/signin?next=/mysteries/younger-dryas-impact/questions/QST0D51X8AJ1304/did-an-extraterrestrial-impact-or-airburst-occur-at-the%23discussion) Help with this question [ **Propose an answer** Something the evidence could support or rule out ] [ **Propose an answer** Something the evidence could support or rule out ](https://mysteriesdept.com/signin?next=/mysteries/younger-dryas-impact/questions/QST0D51X8AJ1304/did-an-extraterrestrial-impact-or-airburst-occur-at-the%23add-answer) [ **Add evidence** A result for or against an answer ] [ **Add evidence** A result for or against an answer ](https://mysteriesdept.com/signin?next=/mysteries/younger-dryas-impact/questions/QST0D51X8AJ1304/did-an-extraterrestrial-impact-or-airburst-occur-at-the%23add-evidence) [ **Ask a sub-question** A smaller question that would help settle this one ] [ **Ask a sub-question** A smaller question that would help settle this one ](https://mysteriesdept.com/signin?next=/mysteries/younger-dryas-impact/questions/QST0D51X8AJ1304/did-an-extraterrestrial-impact-or-airburst-occur-at-the%23add-question) [ **Add a source** A paper, archive record or image ] [ **Add a source** A paper, archive record or image ](https://mysteriesdept.com/signin?next=/mysteries/younger-dryas-impact/questions/QST0D51X8AJ1304/did-an-extraterrestrial-impact-or-airburst-occur-at-the%23add-source) Where it fits Younger Dryas impact hypothesis **Did an extraterrestrial impact or airburst occur at the onset of the Younger Dryas, about 12,800 years ago?** Key question · you're here [Are the proposed markers (microspherules, nanodiamonds, shocked quartz, meltglass) reproducible and diagnostic of impact?](https://mysteriesdept.com/mysteries/younger-dryas-impact/questions/QST0D51X8T620G9/are-the-proposed-markers-microspherules-nanodiamonds-shocked)Most likely · the markers are background cosmic dust, volcanic or anthropogenic spherules, fire products or misidentified… [Is the claimed boundary layer the same age at every site?](https://mysteriesdept.com/mysteries/younger-dryas-impact/questions/QST0D51X8JC0DHZ/is-the-claimed-boundary-layer-the-same-age-at-every-site)Most likely · the claimed layers are of different ages, or their ages are not known well enough to say [ Ask a question under this one ]